The good news is that influenza was very scarce last year (2020-21) in the Northern Hemisphere and remained scarce this summer in the Southern Hemisphere. As well described by Uyeki et al (doi:10.1001/jama.2021.6125), this could generally be attributed to three factors: 1) community mitigation measures (e.g., masking, social distancing, workplace closures, school closures, virtual school instruction, indoor dining restrictions), 2) behavioral changes (e.g., staying at home, working from home, reduced domestic and international travel, or international travel with subsequent quarantine upon arrival, and 3) influenza vaccination. Last flu season set a record for vaccine distribution (194 million doses), with more than 55% of adults getting immunized in the U.S. What to expect this year? Anything from a repeat of last season's numbers to an explosion of cases is possible.
Let's look at the first factor, community mitigation measures. Schools are open, which means that children are in a position to accelerate the transmission of influenza in the community. Many people who are vaccinated against COVID-19 have eased masking and social distancing, increasing their exposure to influenza. Indoor dining is almost back to normal, where social distancing and masking are difficult to follow. Let's look at the second factor, behavioral changes. People are more comfortably resuming normal activities because they are vaccinated against COVID-19, including international and domestic air travel. All of these make factor three, influenza vaccination, more important than ever. The CDC released the new Prevention and Control of Seasonal Influenza with Vaccines recommendations for the 2021-22 influenza season last week. Here are a few takeaways:
Routine annual seasonal influenza immunization is recommended for all persons aged ≥6 months who do not have contraindications
No preferential recommendation is made for one influenza vaccine product over another
Vaccination should be offered by the end of October and continued through flu season
For nonpregnant adults, early vaccination (i.e., in July and August) should be avoided unless there is concern that later vaccination might not be possible
Revaccination later in the season of persons already vaccinated is not recommended
COVID-19 vaccines can be co-administered with influenza vaccines
Influenza vaccine formulations available:
New recommendations regarding severe allergy to influenza vaccines:
Can consider 3 different groups: egg-based vaccines, cell-cultured, and recombinant
Precaution use should occur in an inpatient or outpatient medical setting under the supervision of a provider who can recognize and manage a severe allergic reaction
Influenza season typically peaks between Christmas and Valentine's day, most often closer to Valentine's day. Get your flu vaccine by November and be ready for Christmas and Valentine's day!
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